Cancer can develop in any organ or tissue, and is highly refractory and lethal. It goes with saying that cancer is a very troublesome disease. Recent statistical data showed that one out of every two persons is diagnosed with cancer during life, and one out of four men and one out of six women die of cancer. Thus, cancer remains an extremely severe disease.
To date, a number of anticancer agents have been developed and prescribed to many cancer patients, and certain therapeutic outcome has been achieved. However, anticancer agents are well known to cause serious side effects as well. Meanwhile, it has long been known that there are individual differences in the response to anticancer agents, i.e., therapeutic effects and side effects, although the cause remains undissolved.
Recent advances in science and technology, in particular, rapid progress of pharmacogenomics (PGx), has enabled us to understand various diseases including cancer (such as cancer, diabetes, and hypertension) at the molecular level. It has been revealed that among patients showing similar symptoms, there are cases where genetic polymorphism (including gene mutation) is involved in the various individual differences observed, for example, differences in the absorption, distribution, metabolism, and excretion of administered pharmaceutical agents, as well as differences in the response at sites of action, differences in pathological conditions, and differences in disease susceptibility.
This suggests that for patients who are already affected with cancer, therapeutic effects can be enhanced and side effects can be reduced, for example, by analyzing the patients' genomic information in advance before administration of anticancer agents, and selecting an agent to be administered and determining the mode of prescription based on the presence or absence of specific genetic polymorphisms.
Likewise, for healthy persons also, genomic information of an individual can be analyzed using pharmacogenomics to predict the person's susceptibility to a disease (likelihood of being affected with a disease) as well as the person's responsiveness to pharmaceutical agents, based on the presence or absence of specific genetic polymorphisms.
This novel type of therapeutic method, which uses specific genetic polymorphisms thus identified or mutant polypeptides resulting from such polymorphisms as a biomarker, is referred to as order-made medicine, tailor-made medicine, personalized medicine, or custom-made medicine, and has been adopted for the clinical development of pharmaceutical products and clinical practice in various countries.
Similarly, agents that target the specific genetic polymorphisms identified as described above or mutant polypeptides resulting from such polymorphisms are referred to as molecularly targeted drugs, and their development is setting off actively.
Fibroblast growth factor receptors (FGFRs) are kinases belonging to the receptor tyrosine kinase family. FGFR1, FGFR2, FGFR3, and FGFR4 constitute the FGFR family. The ligand is fibroblast growth factor (FGF), and 22 types of structurally similar proteins form the family.
Signals transmitted via FGFR are conveyed to the MAPK pathway or PI3K/AKT pathway. It has been reported that in cancer, signal transduction is involved in cell growth, angiogenesis, cell migration, invasion, metastasis, etc.; and FGFR is activated as a result of overexpression, gene hyper-amplification, mutation, or translocation (Non-patent Document 1). For example, it is known that for FGFR3, genetic translocation is observed in multiple myeloma (Non-patent Document 2); gene mutation is observed in bladder cancer (Non-patent Document 3); and overexpression is observed in ovarian cancer, non-small cell lung carcinoma, and hepatocellular carcinoma.
The findings described above suggest a connection between FGFR and cancer. Thus, attempts have been made to develop compounds with FGFR inhibitory activity as anticancer agents (Non-patent Documents 4 and 5).
While it has been reported very recently that genetic translocation that suggests the presence of a fusion polypeptide of FGFR3 and transforming acidic coiled-coil protein 3 (TACC3) or a fusion polypeptide of FGFR1 and TACC1 was found in very few cases of brain tumor glioblastoma multiforme (GBM) (three of 97 samples, 3.1%) (Non-patent Document 6), the connection between fusion polypeptides of FGFR with other proteins and other types of cancer remains unclear.